The present invention relates to a process for the catalytic oxidation of polynuclear aromatic hydrocarbons in general and athracene in particular.
The catalytic oxidation of anthracene is used to prepare anthraquinone. Anthraquinone is a valuable intermediate in the preparation of stable dyes for the dye industry. It has also been suggested for use as a pulping accelerator in the paper industry.
Catalytic oxidation has also been suggested as a step in the process of upgrading a mixture of polynuclear aromatic hydrocarbons. In order to upgrade polynuclear aromatic hydrocarbons, such anthracene, to more desirable mononuclear aromatic hydrocarbons, such as benzene, it has been suggested that the polynuclear aromatic hydrocarbons' reactive center rings be first weakened, and then cracked. Catalytic oxidation of the polynuclear aromatic hydrocarbons is one possible way to weaken the polynuclear aromatic hydrocarbons' center rings prior to cracking.
The catalytic oxidation of polynuclear aromatic hydrocarbons in general and anthracene in particular is taught by Daly in U.S. Pat. No. 4,234,749. Daly discloses both the preparation of anthraquinone by the catalytic oxidation of polynuclear aromatic hydrocarbons as a first step in a process for upgrading a mixture of polynuclear aromatic hydrocarbons to benzene. In Daly's process, the oxidizing agent is an oxygen-containing gas, and the catalyst is, inter alia, a ceric ammonium nitrate catalyst system including a potasium chlorate promoter. The oxidation proceeds at an elevated temperature of from about 65.degree. to about 205.degree. C. (149.degree.-401.degree. F.), and in the absence of water. Under these conditions, Daly reports that the turnover ratio, i.e., the number of moles of anthracene converted per mole of catalyst used, is increased several times over that used in prior art catalytic processes for converting anthracene to anthraquinone. (The entire disclosure of U.S. Pat. No. 4,234,749 is hereby incorporated by reference.)
While Daly discloses examples wherein a turnover ratio as high as 1.30 was achieved, further increase inthe turnover ratio is desirable. By increasing the turnover ratio the amount of catalyst consumed by the oxidation reaction can be reduced, thereby decreasing production costs of the overall processes.